Worm Breeder's Gazette 11(4): 34

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

The Complete Nucleotide Sequence of the Retrovirus-Related Element TAS Present in the Genome of Ascaris lumbricoides

H. Felder, A. Herczeg, P. Aeby, F. Mller and H. Tobler

The proretrovirus like element TAS is found in about 50 copies in 
the haploid genome of the nematode A.  Lumbricoides.  One complete 
copy was sequenced.  The putative gag region near the 5' LTR contains 
a 1962 bp long open reading frame which codes for a RNA binding domain.
Near the center of the element we found on the +1 frame (relative to 
the gag frame) a region which shares some characteristics with known 
pol genes.  However, this part of the sequence is interrupted by four 
stop codons.  One of the putative polypeptides contains.the amino acid 
sequence YVDN, a slightly mutated version of the box YXDD which is 
present in almost all known reverse transcriptases.  We conclude that 
stop codons as well as the change in the sequence of the YXDD box are 
the result of occasional point mutations and that the sequenced 
element may represent a nonfunctional copy of TAS.  The YVDN box is 
carboxyterminally flanked by a conserved RNase H and a zinc finger 
motif.  The latter characterizes a possible endonuclease domain.  A 
further 2061 base pair spanning ORF near the 3' LTR of TAS corresponds 
to an env region.  TAS represents obviously a retrovirus related 
sequence with a similar gene arrangement as, e.g., that of the mobile 
element 17.6 in the Drosophila genome and that found in some genomes 
of retroviruses.